Microplastics in freshwater systems. presence, origins and ecological effects

Transcription

1 Microplastics in freshwater systems presence, origins and ecological effects Alice Horton Centre for Ecology and Hydrology, UK

2 Microplastics what are they? Plastic fragments/pellets/fibres/films <5mm Sources: - Primary: polyethylene/polypropylene microbeads from personal care products and cosmetics, industrial pellets - Secondary: Breakdown of large litter, shedding of nylon/polyester fibres (laundry)

3 Microplastics - why study them? Microplastics are everywhere! Rivers and land recognised as sources but little studied Sewage treatment works do not capture these small particles Can be ingested by organisms Act as vectors for transport of persistent organic pollutants (POPs)

4 Inputs to rivers in the UK Storm drain input Effluent input ( grey water ) Combined Sewage Overflows (raw sewage) Land runoff Drainage ditches (agricultural) Litter Photo: James Miller

5 Microplastics in wastewater and sewage sludge Removal efficiency of microplastics following wastewater treatment processes: 99% (Magnusson and Norén 2014) 98% (Murphy et al, 2016) 95% (Talvitie et al, 2017) 97% (Mintenig et al, 2017) However due to large volumes processed, one large STW could still release approx. 900, ,000,000 MPs per day!

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7 Environmental transport of microplastics Horton et al (2017). Science of the Total Environment

8 Microplastics in the Thames river basin, UK a study 4 sites chosen: 2 dirty (> 25% effluent on average) and 2 clean (< 4% effluent on average) 4 replicate sediment samples Size fractions 1-2mm and 2-4mm Sorted visually and by density separation to ensure all particles were encountered. Flotation and filtration system for extracting microplastics from sediment, Alice Horton Floated sediment Floated plastic particles Horton et al (2017). Marine Pollution Bulletin

9 Microplastics: sample sorting and analysis Increasing effluent load Horton et al (2016). Marine Pollution Bulletin

10 Microplastics Raman spectroscopy - Polypropylene - Unknown particle - Copper phthalocyanine - Unknown particle

11 Microplastics exposure Depending on the environment and organisms, exposure will occur in different ways. Numerous variables influence organisms exposure, including: - Proximity to source - Habitat - Behaviour - Feeding habits In addition to polymer characteristics including: - Polymer type - Particle size - Biofouling Effects fall into 2 main categories: Physical damage & chemical damage These can occur in combination.

12 Our approach to fish sampling: The UK National Fish Tissue Archive In 2007, CEH and the UK Environment Agency (EA) began to build an archive of fish tissue samples from a selection of English rivers. EA monitor fish stocks annually normally: throw all back now: give us 10 roach (10 cm+) from selected sites Size, weight and gender recorded Frozen on site (liquid N2) Vacuum packed and stored at -80 C Fish dissected and gut removed Gut contents analysed for microplastics Slide adapted from an original by Monika Juergens

13 Common roach in the Thames - fish gut analysis Location Distance downstream Cricklade Castle Eaton Sandford-Abingdon Caversham-Sonning Temple-Marlow Shepperton-Sunbury Sunbury-Molesey

14 Roach gut analysis - results Average plastics in gut vs distance from source Polymers identified as: Polyethylene Polypropylene Polyester Microplastics are ingested! Differences in ingestion based on: 1. Gender 2. Size of fish

15 Ingestion of microplastics and chemical bioaccumulation Freshwater midge larvae Chironomus sancticaroli 1% by mass nylon, µm PBDEs: 47, 99, 100, 153 Etc see Elma s presentation Horton et al., SETAC Europe 2016

16 Microplastics in terrestrial environments No known studies quantifying microplastics in the terrestrial environment Plastic litter breaks down in the environment Microplastics (beads and fibres) enter terrestrial environment via sewage sludge application to land High potential for retention Photo: Alice Horton Photo: Alex Walton

17 Difficulties in microplastics research Definition of microplastics very broad! What is a plastic? A pure polymer? Any composite containing plastic? Different polymers, sizes, shapes, ages will behave differently and have different effects. Environment will determine ecological interactions Comparability between studies: different methods Sampling Particle extraction Minimum and maximum size counted Particle identification Many studies rely on visual identification very subjective Environmental studies are time-consuming!

18 Thank you Acknowledgements: Alex Walton, Elma Lahive, Dave Spurgeon, Claus Svendsen, Richard Williams, Monika Juergens, Angela Palacio, Lindsay Newbold, Rodrigo G. Disner, Mário A. Navarro-Silva. I have credited photos where possible, apologies where credit was not available and has not been given.

19 References Horton, A. A., Walton, A., Spurgeon, D. J., Lahive, E., & Svendsen, C. (2017). Microplastics in freshwater and terrestrial environments: Evaluating the current understanding to identify the knowledge gaps and future research priorities. Science of The Total Environment (in press). Horton, A. A., Svendsen, C., Williams, R. J., Spurgeon, D. J., & Lahive, E. (2017). Large microplastic particles in sediments of tributaries of the River Thames, UK - Abundance, sources and methods for effective quantification. Marine Pollution Bulletin, 114(1), Horton A. A., Palacio-Cortes A. M., Lahive E., Newbold L., Pereira M. G., Disner R. G., Navarro-Silva M. A., Grassi M. T., Spurgeon D. J. Ingestion of microplastics by the chironomid Chironomus sancticaroli and effects on the microbiome in the presence of PBDEs. In: SETAC Europe 26th Annual Meeting, Nantes, France, May 2016 Magnusson, K., Norén, F. (2014). Screening of microplastic particles in and down-stream a wastewater treatment plant. IVL Swedish Environmental Research Institute, C 55. Mintenig, S.M., Int-Veen, I., Loder, M.G., Primpke, S., Gerdts, G. (2017). Identification of microplastic in effluents of waste water treatment plants using focal plane array-based micro-fourier-transform infrared imaging. Water Research 108, Murphy, F., Ewins, C., Carbonnier, F., Quinn, B. (2016). Wastewater Treatment Works (WwTW) as a Source of Microplastics in the Aquatic Environment. Environmental Science & Technology 50, Talvitie, J., Mikola, A., Setala, O., Heinonen, M., Koistinen, A. (2017). How well is microlitter purified from wastewater? - A detailed study on the stepwise removal of microlitter in a tertiary level wastewater treatment plant. Water Research 109, Additional reading: Boucher, J., Friot, D., Primary Microplastics in the Oceans: a Global Evaluation of Sources. IUCN, Gland, Switzerland. Carr, S.A., Liu, J., Tesoro, A.G., Transport and fate of microplastic particles in wastewater treatment plants. Water Res. 91, Ziajahromi, S., Neale, P.A., Leusch, F.D., Wastewater treatment plant effluent as a source of microplastics: review of the fate, chemical interactions and potential risks to aquatic organisms. Water Sci. Technol. 74,